Processing apparatus, method for fabrication of semiconductor device by using the processing apparatus, and semiconductor device fabricated by this method

ABSTRACT

The processing apparatus in accordance with the present invention comprises an object holding unit for holding a processing object, a tool holding unit for holding a tool for processing the processing object, and a relative movement mechanism for causing relative movement of the processing object held in the object holding unit and the tool held in the tool holding unit, while maintaining contact therebetween. The object holding unit and/or the tool holding unit are composed of a plurality of support plates of almost flat shape having elastic property which are arranged in a row.

FIELD OF THE INVENTION

The present invention relates to a processing apparatus comprising anobject holding unit for holding a processing object, a tool holding unitfor holding a tool for processing the processing object, and a relativemovement mechanism for causing relative movement of the processingobject held in the object holding unit and the tool held in the toolholding unit, while maintaining contact therebetween. The presentinvention also relates to a method for the fabrication of asemiconductor device in which the processing object is a semiconductorwafer and the processing apparatus is used as a polishing apparatus forpolishing of the semiconductor wafer and also to a semiconductor devicefabricated by this method.

BACKGROUND OF THE INVENTION

Examples of the aforementioned processing apparatuses include polishingapparatuses in which a semiconductor wafer serving as a processingobject is held with a holding unit and surface polishing of thesemiconductor wafer is conducted by causing relative rotational movementof the semiconductor substrate and a polishing tool (polishing pad),which is a processing tool, while maintaining contact therebetween.Polishing apparatuses for conducting surface polishing of semiconductorwafers in the above-described manner are required to carry out extremelyaccurate and uniform polishing. For this reason, care was taken tomaintain constantly the optimum processing state by employing aconfiguration in which a polishing tool changed the posture thereofaccording to peaks and valleys of the wafer (processing object) surfaceor the wafer changed the posture thereof.

For example, in the polishing apparatus disclosed in U.S. Pat. No.6,251,215, a highly flexible rubber sheet is used in the head portionfor holding the wafer and the wafer is pressed against the polishing padserving as a polishing tool via the rubber sheet by applying airpressure to the back surface side of the rubber sheet. Furthermore, inthe apparatus disclosed in Japanese Patent Application Laid-open No.H10-235555, a head portion for holding a wafer is linked to a rotarydrive shaft via a ball joint structure and the head portion is rotarydriven via the ball joint unit so that it is free to swing. Using theaforementioned rubber sheet or ball joint structure allows the wafer tochange pliably the posture thereof according to peaks and valleys on thesurface thereof, the wafer is in constant and uniform contact with thepolishing pad, and uniform surface polishing can be conducted.

By contrast with the above-described configuration, an apparatus is alsoknown which is so constructed that the polishing tool, that is, thepolishing pad can pliably change the posture thereof (Japanese PatentApplication Laid-open No. H11-156711). In this apparatus, a wafer isvacuum suction attached to a wafer chuck, so that the surface of thewafer which is to be polished faces up (face-up state), and rotatestogether with the wafer chuck. A polishing head is disposed opposite thewafer and above it. The polishing head comprises a pad plate havingpasted thereon a polishing pad which is to be in contact with the wafersurface which is to be polished, a drive plate and a rubber sheet(diaphragm) for flexibly supporting the pad plat, and a head housinghaving formed therein an inner space for constituting a pressure chamberfor applying the air pressure to the aforementioned components. Theouter periphery of the drive plate and rubber sheet are joined at theouter periphery of the lower edge of the head housing, the drive plateand rubber sheet are joined with the pad plate in the inner peripheralportion thereof, and the inner space of the head housing is covered bythose drive plate and rubber sheet, thereby forming the pressurechamber. As a result, the pad plate is supported by the head housing viathe drive plate, and a pressure is uniformly received inside thepressure chamber via the rubber sheet. If the head housing is rotarydriven, then the rotary driving force is transmitted to the pad platevia the drive plate, and the entire configuration is rotated.

A process for polishing a wafer by using such a polishing apparatus isconducted by bringing the polishing pad into contact with the surface ofthe wafer which is suction held by the wafer chuck, while rotating thehead housing. In this process, the head housing is moved sidewise in aplane and the entire surface of the wafer is uniformly polished. Whenthe wafer surface is thus polished, the drive plate is required to havesufficient flexibility in the up-down direction (thickness direction) sothat the polishing pad can pliably change the posture thereof accordingto peaks and valleys of the substrate surface. The drive plate isfurther required to allow the head housing and pad plate to be rotatedby transmitting the rotary drive force (drive torque for processing) ofthe head housing via the pad plate and to have a strength and endurancesufficient to withstand the action of the rotary drive force or contactresistance (resistance torque during processing) between the polishingpad and wafer during rotation.

As described hereinabove, the outer periphery of the drive plate isjoined to the outer periphery of the lower end of the pad housing andthe pad plate is engaged with the inner periphery of the drive plate.Therefore, the pad plate moves in the up-down direction with respect tothe pad housing because the inner periphery moves in the directionperpendicular to the drive plate surface with respect to the outerperiphery of the drive plate due to elastic deformation thereof. Thus,large movement caused by elastic deformation in the directionperpendicular to the plane on the inner periphery with respect to theouter periphery of the drive plate means that the drive plate has a highdegree of flexibility in the up-down direction. In order to provide thedrive plate with such large flexibility in the up-down direction, aconfiguration was used, for example, as shown in FIG. 19, in which thedrive plate 100 was produced by forming a disk with a round hole in thecenter from a thin metal sheet and then forming multiple openingspositioned on concentric circles in the disk. In such a drive plate 100,when the outer periphery 102 is joined and held on the outer peripheryof the lower end of the pad housing, the inner periphery 101 where thepad plate is joined can be elastically deformed to a large degree in theup-down direction and, therefore, the drive plate has large flexibilityin the up-down direction.

However, the requirements placed on flexibility of the drive plate inthe up-down direction and strength and endurance against the resistancetorque or drive during processing are mutually exclusive and aredifficult to satisfy at the same time. For example, as shown in FIG. 19,flexibility in the up-down direction can be increased by providingmultiple openings 103 in the drive plate 100. However, if the number orsize of the openings 103 is too large, then strength against theresistance torque or drive during processing decreases and the driveplate can be deformed or fractured. In particular, because the openings103 in the drive plate 100 are subjected to cyclic stresses duringprocessing, there is a risk of those cyclic stresses causing fatiguedamage and fracture (for example, damage and fracture such as a crack100 a shown in FIG. 19).

Furthermore, large flexibility of the drive plate in the up-downdirection is required not only for tracing the peaks and valleys on thewafer surface during processing, as described hereinabove, but also fromthe following standpoint. First, if polishing is conducted by pressing apolishing pad against the wafer surface, then the polishing pad surfaceis worn and thinned as the wafer surface is polished. The problemassociated with this effect is that the amount of deformation of thedrive plate in the up-down direction increases accordingly, arestoration force in the up-down direction is generated to restore theoriginal shape, this force acts in the direction opposite that of theair pressure created by the pressure chamber, and the contact pressurebetween the polishing pad and wafer surface changes (decreases). Inorder to minimize these changes in contact pressure, it is desired thatthe flexibility of the drive plate in the up-down direction beincreased, that is, that the elastic constant relating to elasticdeformation in the up-down direction be decreased.

Further, in order to minimize the effect of the restoration forcegenerated by such deformation of the drive plate in the up-downdirection, the adjustment is conducted so that the drive plate assumes aneutral position (position in which the restoration force does not act)in a state where the polishing pad is brought into contact with thewafer surface which is to be polished, before the polishing is started.However, the accuracy of such adjustment is limited. Furthermore,because of a spread in thickness of the pad plate and polishing pad, theposition of the drive plate unavoidably shifts to a certain extent fromthe neutral position in the up-down direction after the processing isstarted. As a result, a certain restoration force acts after theprocessing has been started. In order to resolve these problems, it isdesired that the flexibility of the drive plate in the up-down directionbe increased within a range of satisfactory endurance, that is, that theelastic constant relating to elastic deformation in the up-downdirection be decreased.

Furthermore, a high polishing accuracy of wafer surface cannot beattained by merely increasing the flexibility of the drive plate in theup-down direction. More specifically, it is necessary to hold thepolishing pad and wafer surface parallel to each other and to providethe drive plate with an appropriate flexibility in the inclineddirection, that is, to ensure a suitable rigidity thereof, so that thepolishing pad and wafer surface maintain intimate contact duringpolishing. This issue was not heretofore given much attention, and atthe stage of designing the drive plate, the principle emphasis was onflexibility in the up-down direction. For this reason, when thepolishing pad protruded from the wafer surface and overhung duringswinging of the polishing head, the drive plate could not provide arestoration force sufficient to check a momentum force acting upon thepolishing pad, the positioning pad tilted, and eventually stressconcentration occurred in the edge portions of the wafer. Such stressconcentration at the edge circumference is typically called “edgeexclusion”. Because it produces an excess polishing region, thepolishing rate becomes much higher in this region than in other placesand this region cannot be employed as a device region. This rises aproblem with brittle materials such as low-k materials that haverecently become materials of choice, because the structure itself can becompression fractured by stress concentration.

Yet another problem associated with the conventional drive plate is thatthe so-called chatter vibrations originate in the polishing pad, andthese vibrations make it necessary to interrupt the polishing process.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a processingapparatus in which the rigidity of the drive plate in the up-downdirection can be decreased, while maintaining sufficient strength andendurance during polishing.

Another object of the present invention is to provide a processingapparatus that ensures correct rigidity of the drive plate in theinclined direction.

Yet another object of the present invention is to provide a processingapparatus with a structure such that makes it possible to suppressvibrations of the polishing pad.

The processing apparatus in accordance with the present invention,comprises an object holding unit (for example, a substrate holding table95 in the embodiment) for holding a processing object (for example, asubstrate 90 in the embodiment), a tool holding unit (for example, apolishing head 30 in the embodiment) for holding a tool (for example, apolishing tool 50 having a polishing pad 60 mounted thereon in theembodiment) for processing the processing object, and a relativemovement mechanism (for example, a support frame 20 in the embodiment)for causing relative movement of the processing object held in theobject holding unit and the tool held in the tool holding unit, whilemaintaining contact therebetween, wherein the object holding unit and/ortool holding unit are composed of a plurality of support plates (forexample, a drive plate 33 in the embodiment) of almost flat shape havingelastic property which are arranged in a row. It is especially preferredthat a plurality of support plates be disposed by stacking in a row inthe plate thickness direction.

Thus, in the processing apparatus in accordance with the presentinvention, the support plates such as drive plates are used uponstacking a plurality thereof in the up-down direction (plate thicknessdirection). For example, let us consider a case in which two driveplates are stacked. FIG. 3 is a schematic sectional view illustratingthe main elements peripheral to the processing tool (polishing tool) 50of the processing apparatus in accordance with the present invention.The processing tool 50 is supported in the center of the support plate(drive plate) 33 and is attached to the tool holding unit (polishinghead) 30 via the drive plate 33. Therefore, if the drive plate 33 isdeformed, the polishing tool 50 shifts accordingly. Here, in case of twodrive plates 33, the configuration can be considered as a parallelspring in which plate springs 33 a, 33 b are arranged in a row one abovethe other and fixed at both ends thereof with mixing members 33 c, asshown in FIG. 4. The properties of a parallel spring are such that theamount of displacement (amount of curving) caused by a force acting inthe up-down direction is half that of one plate spring, whereas thedisplacement caused by a force acting in the inclined direction is muchless than half that of one plate spring. Thus, in a parallel spring, therigidity in the inclined direction is greater than that in the up-downdirection. This difference becomes more significant with the increase inthe number of plate springs. Therefore, if a plurality of the driveplates are arranged by stacking in a row so as to obtain a parallelspring configuration, then the rigidity in the up-down direction andrigidity in the inclined direction can be independently controlled andset to a desired balance by controlling the thickness and number of thedrive plates. For example, if a randomly selected drive plate iscompared with a configuration obtained by stacking two drive plateswhich has a thickness of 1/³{square root}{square root over ( )}2 of theselected drive plate, the rigidity in the up-down direction will be thesame, but the rigidity of the former configuration in the inclineddirection is substantially higher than that of the single drive plate.Therefore, the present invention makes it possible to increase easilyonly the rigidity in the inclined direction. Furthermore, in theprocessing apparatus in accordance with the present invention, aplurality of support plates may be disposed by lining them up parallelto each other with a prescribed spacing and stacking in the platethickness direction, and it is preferred that each of a plurality ofsupport plates is provided with one or more openings for providing theplate with elastic properties.

Further, stacking a plurality of support plates (drive plates) alsocontrols the above-described chatter vibrations caused by resonance,that is, demonstrates a vibration suppressing effect on the processingtool. First, vibrations caused by external forces acting in the inclineddirection, are suppressed by the increase in rigidity in the inclineddirection due to the increase in the number of drive palter. Further, ifthe number of drive plates is increased, then the vibrations of driveplates will interfere with each other and vibrations in the inclineddirection and up-down direction (plate thickness direction) can beattenuated. Therefore, it is preferred that in the support plate of theprocessing apparatus in accordance with the present invention, aplurality of support plates be disposed by stacking in the platethickness direction, so that the openings in the support plates thatadjoin each other in the up-down direction are shifted with respect toeach other. This is because when the openings in the stacked supportplates (drive plates) are disposed with a displacement with respect toeach other, the places in the plates that face each other have differentphases of deformation. A configuration may be used in which the openingsproviding the plate with elastic property are formed in at least twosupport plates of a plurality of support plates, and the patterns of theopenings in the two support plates differ, if viewed from the platethickness direction of the support plates.

Further, it is also preferred that in the processing apparatus inaccordance with the present invention, at least part of the openings beformed by a chemical removal process. With the processing apparatus ofsuch configuration, because the openings are formed by a chemicalremoval process, the occurrence of strain concentration at the peripheryof the openings can be suppressed, the strength and endurance againstthe resistance torque and drive torque during processing can be improveddespite the increased number and size of the openings, flexibility inthe up-down direction (direction perpendicular to the plate surface) ofthe support plate is increased and strength and endurance can beensured.

Furthermore, it is preferred that the chemical removal process beetching and that the average surface roughness of the support platessubjected to the chemical removal process be 0.2 a or less. It isfurther desirable that the openings formed by the chemical removalprocess be chamfered by barrel polishing or after-etching.

The openings in the support plate are composed of curved or linear slitsand almost round open portions formed at the ends of the slits andhaving a diameter larger than the width of the slits. With theprocessing apparatus of such configuration, because the openingscomprise round open portions at the ends of the slits, the occurrence ofstress concentration in the end portions of the openings is suppressed,the strength and endurance against the resistance torque and drivetorque during processing can be improved despite the increased numberand size of the openings, flexibility in the up-down direction(direction perpendicular to the plate surface) of the support plate isincreased and strength and endurance can be ensured. Therefore, theopenings may be composed of curved or linear slits and portions with ashape reducing shear stresses to which the support portion is subjectedwhen the processing object is processed with the tool.

Further, in the processing apparatus of the above-describedconfiguration, the support plate is preferably produced from a materialwith a tensile strength of 1000 N/mm² or higher, and this material ispreferably an austenitic stainless steel. Further, the fatigue life ofthe support plate based on the maximum value of the equivalent stressamplitude to which the support portion is subjected when the processingobject is processed with the tool is no less than the actual use periodof the processing apparatus. Moreover, it is preferred that at least thesupport plate be placed in vacuum environment or environment of asubstance with low chemical reactivity with respect to the constituentmaterials of the support plate during processing of the processingobject with the tool.

On the other hand, in the method for the fabrication of a semiconductordevice in accordance with the present invention, the processing objectis a semiconductor substrate and the method comprises the step ofplanarizing the surface of the semiconductor substrate by using theprocessing apparatus of the above-described configuration. Further, thesemiconductor device in accordance with the present invention isfabricated by this method for the fabrication of a semiconductor device.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given herein below and the accompanying drawingswhich are given by way of illustration only and thus are not limitativeof the present invention.

FIG. 1 is a front view illustrating the CMP apparatus which is arepresentative example of the processing apparatus in accordance withthe present invention;

FIG. 2 is cross-sectional view illustrating the first embodiment of thepolishing head constituting the CMP apparatus;

FIG. 3 is a schematic cross-sectional view of the polishing head;

FIG. 4 schematically simulates the structure of two stacked drive plateswith a parallel spring;

FIG. 5 is a plan view illustrating an example of a drive plate used inthe polishing head;

FIG. 6 is a perspective view illustrating the shape of a test piece forwhich the S-N curves shown in FIGS. 7 and 8 were found;

FIG. 7 is a graph illustrating the S-N curve relating to the test pieceshown in FIG. 6 that was produced by laser processing and etching fromstainless steel SUS304;

FIG. 8 is a graph showing the relationship between the equivalent stressamplitude σeq, mean stress σm, and cyclic stress amplitude σa;

FIG. 9 is a graph illustrating the S-N curve relating to the test pieceshown in FIG. 6 that was produced by laser processing and etching fromstainless steels SUS304 and SUS301;

FIG. 10 is a graph illustrating the relationship between tensilestrength and fatigue limit;

FIG. 11 is an analytical drawing illustrating the pattern ofdeformations in the up-down direction and inclined direction of thedrive plate analogous to the drive plate shown in FIG. 3;

FIG. 12 illustrates a deformation state of one of the two stacked driveplates;

FIG. 13 illustrates a deformation state of the other of two stackeddrive plates, this figure shows a pattern obtained by shifting the driveplate shown in FIG. 11 through 36° in the rotation direction;

FIG. 14 shows one of the two drive plates provided with multiple spiralgrooves;

FIG. 15 shows the other of the two drive plates provided with multiplespiral grooves, this figure shows a pattern obtained by forming thespiral grooves with the winding direction opposite to that of the driveplate shown in FIG. 14;

FIG. 16 shows a modification example of the drive plate shown in FIG.14;

FIG. 17 shows a modification example of the drive plate shown in FIG.15;

FIG. 18 is a flowchart illustrating a process for the fabrication of asemiconductor device;

FIG. 19 is a plan view illustrating the shape of the conventional driveplate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will be describedhereinbelow with reference to the appended drawings. A CMP apparatus(chemical-mechanical polishing apparatus) which is a representativeexample of the polishing apparatus in accordance with the presentinvention is shown in FIG. 1. This CMP apparatus 1 comprises a waferholding table 95 which can detachably attach and hold a wafer 90 as apolishing object on the upper surface side thereof and a polishing head30 which is disposed in the position above the wafer holding table 95and holds a polishing member 50 having a polishing pad 65 mountedthereon, this polishing pad facing the polish surface 91 of the wafer 90held on the wafer holding table 95. In this CMP apparatus 1, the size(diameter) of the polishing pad 65 is less than the size (diameter) ofthe waver 90, which is the polishing object (in other words, thepolishing pad 65 has a smaller diameter than the wafer 90) and theentire polish surface (upper surface) 91 of the wafer 90 can be polishedby moving the polishing pad 65 with respect to the wafer 90, whilemaintaining contact therebetween.

A support frame 20 for supporting those wafer holding table 95 andpolishing pad 30 comprises a horizontal stand 21, a first stage 21 soprovided that it can move in the Y direction along a rail (not shown inthe figure) provided in the extending condition in the Y direction(direction perpendicular to the paper sheet, this direction isconsidered as a front-rear direction) on the stand 21, a vertical frame23 so provided as to extend vertically (Z direction) from the firststage 22, a second stage 24 so provided that it is free to move alongthe Z direction (up-down direction) on the vertical frame 23, ahorizontal frame 25 so provided as to extend horizontally (X direction)from above the second stage 24, and a third stage 26 so provided that itcan move in the X direction (left-right direction) on the horizontalframe 25.

A first electric motor M1 is provided in the first stage 22 and rotarydriving the motor makes it possible to move the first stage 22 in the Ydirection along the rail. A second electric motor M2 is provided in thesecond stage 24 and rotary driving the motor makes it possible to movethe second stage 24 in the Z direction along the vertical frame 23. Athird electric motor M3 is provided in the third stage 26 and rotarydriving the motor makes it possible to move the third stage 26 in the Xdirection along the horizontal frame 25. Therefore, the third stage 26can be moved to any position above the wafer holding table 95 bycombining the rotary operation of the electric motors M1 to M3.

The wafer holding table 95 is mounted horizontally on the upper endportion of a rotary shaft 28 provided in extending condition verticallyupward from a table support portion 27 provided on the stand 21. Therotary shaft 28 is rotated by rotary driving a fourth electric motor M4provided inside the table support unit 27, thereby making it possible torotate the wafer holding table 95 in the XY plane (horizontal plane).

The polishing head 30 is mounted on the lower end portion of a spindle29 provided in extending condition vertically downward from the thirdstage 26. The spindle 29 is rotated by rotary driving a fifth electricmotor M5 provided inside the third stage 26. As a result, the entirepolishing head 30 can be rotated and the polishing pad 65 can be rotatedin the XY plane (horizontal plane).

Further, the polishing head 30, as shown in FIG. 2, comprises anopen-end cylindrical head housing 10 having an opening at the lowersurface side which is linked via a linking member 11 with bolts B1 tothe lower end portion of the spindle 29, a holding ring 31 mounted byusing bolts B2 on the upper side portion inside the head housing 10, aring member 32 mounted by using bolts B3 on the lower surface side ofthe holding ring 31, a disk-like drive plate 33 sandwiched at the outerperipheral portion thereof between those holding ring 31 and ring member32, and the polishing member 50 mounted upon positioning on the lowersurface side of the drive plate 33. Further, the opening of the headhousing 10 is sealed by the polishing member 50 and a pressure chamberH1 is formed inside the head housing 10.

An air suction orifice 12 is formed in the central portion of thelinking member 11 and the air from the air supply channel 80 so formedas to pass through the center inside the spindle 29 is passed throughthis air suction orifice 12 and supplied into the head housing 10(pressure chamber H1). Further, the air supply channel 80 is connectedto an air supply source (not shown in the figures) and the air pressureinside the head housing 10 can be adjusted to the desired pressure withthe air supplied form the air supply source.

The drive plate 33 is produced from a metal sheet such as an austeniticstainless steel sheet. In this drive plate, as shown in detail in FIG.5, multiple openings 33 b, c arranged along the concentric circles areformed, as shown in the figure, in the disk having a round hole 33 aformed in the center thereof. Each opening 33 b is composed of a slit 33d extending in the circumferential direction and round open portions 33g having a diameter larger than the slit width and formed at both endsof the slit 33 d. The openings 33 c formed on the innermost peripheryand outermost periphery are composed only of slits 33 d. As for theopenings 33 b in the intermediate portions, because stresses generatedat both ends of slits 33 d increase when a wafer is polished, the roundopen portions 33 g are provided to prevent stress concentration andreduce the generated stresses. On the other hand, in the slits 33 c onthe innermost periphery and outermost periphery, stresses generatedduring polishing are small and it is suffice to employ only the slits 33d. Furthermore, the drive plates 33 are arranged as a stack of two driveplates in the up-down direction (plate thickness direction). Such atwo-plate arrangement will be described below.

The polishing member 50 comprises a disk-like reference plate 51positioned and mounted on the lower surface side of the drive plate 33and a polishing tool 60 detachably mounted by vacuum suction on thelower surface of the reference plate 51. The reference plate 51 isformed as a disk provided with a step wherein the outer diameter of theupper portion thereof is slightly less than the inner diameter of thering member 32, and the outer diameter of the lower portion thereof issomewhat less than the inner diameter (that is, the opening diameter) ofa flange 10 a at the lower end of the head housing 10. Further, thereference plate 51 closes the opening of the head housing 10, seals theinside of the head housing 10, and forms the pressure chamber H1 insidethe head housing 10.

A disk-like central member 55 having a radius somewhat less than that ofthe round hole 33 a of the drive plate 33 is fixed with bolts B4 to theupper surface side in the central portion of the reference plate 51, andthe inner peripheral portion of the drive plate 33 which is aligned withthis central member 55 is sandwiched between the reference plate 51 anda fixing ring 56 fixed with bolts B5 to the upper surface side of thereference plate 51. The reference plate 51 is thus fixed to the headhousing 10 via the drive plate 33, and the rotary drive force of thespindle 29 is transmitted to the reference plate 51 via the drive plate33.

Further, the outer diameter of a flange 51 a protruding outwardly fromthe outer peripheral portion of the reference plate 51 is larger thanthe inner diameter of the flange 10 a protruding inwardly from the innerperipheral portion at the lower end of the head housing 10, and thereference plate 51 is prevented from coming out of the head housing 10.

The polishing tool 60 is composed of a disk-like pad plate 61 having adiameter almost equal to that of the reference plate 51 and a roundpolishing pad (polishing cloth) 65 mounted on the polishing pad mountingsource 61 a which is the lower surface of the pad plate 61. Here,because the polishing 65 is an expendable product which degrades in thecourse of polishing, it is detachably mounted on the polishing padmounting surface 61 a (for example, with an adhesive) and can be easilyreplaced. Further, the lower surface side of the polishing pad 65 servesas a polishing surface 66 facing the polish surface 91 of the wafer 90.

As shown in FIG. 2, an air intake channel 71 having a plurality ofsuction openings at the lower surface side thereof is formed inside thereference plate 51. This air intake channel 71 extends also to thecentral member 55 and opens at the side of the pressure chamber H1 ofthe head housing 10. An intake pipe 72 extending inside the air supplychannel 80 of the spindle 29 is connected to this open portion, and thepad plate 61 can be suction mounted on the reference plate 51 by takingair in from the intake pipe 72 after the pad plate 61 has been placed onthe lower surface side of the reference plate 51. Here, the alignment ofthe pad plate 61 and positioning thereof in the rotation direction isconducted with a center pin P1 and positioning pin P2 provided betweenthe pad plate 61 and reference plate 51.

Furthermore, a polishing agent supply tube 81 connected to a polishingagent supply unit (not shown in the figures) extends in the air supplychannel 80 and is connected via a connection tool 82 positioned betweenthe spindle 29 and the central member 55 to a flow channel 83 soprovided as to pass through the central member 55, a flow channel 84passing through inside the center pin P1, a flow channel 85 providedinside the pad plate 61, and a flow channel (not shown in the figure)provided in the polishing pad 65.

Further, the ring member 32 is formed to have a ring-like shape with aninner diameter slightly larger than the outer diameter of the upperportion of the reference plate 51. This ring member surrounds the upperportion of the reference plate 51 located inside the head housing 10 andis so composed that a prescribed gap S1 appears between the innerperipheral surface of the ring member 32 and the outer peripheralsurface of the upper portion of the reference plate 51. Further, the airpressure inside the pressure chamber H1 is received by the upper surfacein the center of the reference plate 51, and the reference plate 51mounted and held on the lower surface side of the drive plate 33, thatis, the polishing member 50 can move reciprocally in the up-downdirection (toward the polish surface 91).

As a result, because the inner diameter of the ring member 32 isslightly larger than the outer diameter of the upper portion of thereference plate 51, the cross-sectional area of the gap S1 becomesextremely small, and the air located inside the pressure chamber H1 thatwas formed inside the head housing 10 is prevented from flowing out fromthe pressure chamber H1 through this gap S1. Therefore, the pressurechamber H1 can be formed inside the head housing 10, without usingspecial sealing means such as a rubber sheet. The elastic deformation ofthe rubber sheet and the effect of the elastic force thereof on thereference plate 51 (polishing member 50) are thus eliminated. Therefore,the linearity of propulsion force of the polishing member 50 (polishingpad 65) with respect to the air pressure inside the head housing 10 canbe improved. Further, control performance in a pressurizing controlconducted when the polishing pad 65 is pressed against the wafer 90 canbe improved and processing accuracy of the wafer 90 can be increased.

Further, a labyrinth space H2 communicating with the pressure chamber H1via the gap S1 is formed between the lower surface side of the ringmember 32 and the upper surface side of the edge portion of thereference plate 51, and an air release passage 13 linked to thislabyrinth space H2 is formed in the side portion of the head housing 10.The air release passage is formed to extend to an air release opening 14formed at the side surface side of the head housing 10, and the airpresent inside the head housing 10 passes from the labyrinth space H2through the air release passage 13 and air release opening 14 and isreleased to the outside of the head housing 10.

A joint 15 and an air release tube 16 are mounted in the air releaseopening 14, and the air release passage 13 is linked to the air releasetube 16 via the joint 15. The air release tube 16 is linked to a vacuumsource (not shown in the figure) and the air pressure inside the headhousing 10 can be reduced and adjusted to the described pressure. As aresult, because the air release opening 14 is formed separately from theair suction opening 12, the air pressure inside the head housing 10 canbe rapidly reduced and adjusted to the desired pressure, and the controlrate in pressurizing control conducted when the polishing pad 65 ispressed against the wafer 90 can be increased.

In order to conduct polishing of the wafer 90 by using the CMP apparatus1 of the above-described configuration, first, the wafer 90 which is thepolishing object is suction mounted on the upper surface of the waferholding table 95 (in this process, the center of the wafer 90 is alignedwith the rotation center of the wafer holding table 95) and the waferholding table 95 is rotated by driving the electric motor M4. Then, theelectric motors M1 to M3 are driven, the third movement stage 26 ispositioned above the wafer 90, the spindle 29 is driven with theelectric motor M5, and the polishing head 30 is rotated. The electricmotor M2 is then driven, the third stage 26 is lowered, and the lowersurface of the polishing pad 65 (polishing surface) is pressed againstthe upper surface (surface which is to be polished) of the wafer 90.

Then, the air pressure inside the pressure chamber H1 is adjusted andthe contact pressure of the wafer 90 and the polishing pad 65 is set tothe prescribed value by supplying air from the air supply source intothe head housing 10 or releasing the air from the head housing 10 byusing the vacuum source. The electric motors M1, M3 are then driven, andthe polishing head 30 is caused to swing in the XY direction (thein-plane direction of the contact surface of the wafer 90 and thepolishing pad 65). At the same time a polishing agent (liquid slurrycomprising silica particles) is fed under pressure from the polishingagent supply unit and the polishing agent is supplied to the lowersurface side of the polishing pad 65. As a result the polish surface 91of the wafer 90 is polished by the rotary movement of the wafer 90itself and the rotary and swinging movement of the polishing head 30(that is, the polishing pad 65), while the polishing agent is beingsupplied.

When the polish surface 91 of the wafer 90 is thus polished, because thepolishing member 50 comprising the polishing pad 65 is supported by thehead housing 10 via the drive plate 33, the posture of the polishingmember 50 changes according to the inclination or roughness of thepolish surface 91 under the effect of elastic deformation of the driveplate 33, and the polish surface 91 is uniformly polished.

As a result, decreasing the cross-sectional area of the gap S1 betweenthe ring member 32 and reference plate 51 (polishing member 50) makes itpossible to form the pressure chamber H1 inside the head housing 10,without using sealing means such as a rubber sheet, because the airpresent inside the pressure chamber H1 that was formed inside the headhousing 10 is prevented form passing through the gap S1 and flowing outto the outside of the pressure chamber H1. For this reason, the elasticdeformation of the rubber sheet and the effect of the elastic forcethereof on the reference plate 51 (polishing member 50) are thuseliminated. Therefore, the linearity of propulsion force of thepolishing member 50 (polishing pad 65) with respect to the air pressureinside the head housing 10 can be improved. Further, control performancein pressurizing control conducted when the polishing pad 65 is pressedagainst the wafer 90 can be improved and processing accuracy of thewafer 90 can be increased.

Two drive plates 33 were stacked (as described hereinabove), but here wewill first consider the deformation of a single plate 33 and theinternal stresses generated during polishing. As described hereinabove,the drive plate 33 comprises multiple openings 33 b, 33 c′ arrangedalong the concentric circles. Therefore, when a force acts in theup-down direction (direction perpendicular to the drive plate surface)upon the inner peripheral portion 33 h thereof after the outerperipheral portion 33 f thereof has been fixed to the outer periphery atthe lower end of the head housing 10, the amount of deformation in theup-down direction of the inner peripheral portion 33 h caused by elasticdeformation of the drive plate 33 is substantially larger than that whenno openings are provided. Thus, an elastic constant of elasticdeformation of the drive plate 33 in response to the movement of theinner peripheral portion 33 h decreases. For this reason, the polishingtool 50 which is mounted by bonding to the inner peripheral portion ofthe drive plate 33 can move pliably in the up-down direction, thepolishing tool 50 moves or tilts in the up-down direction following theinclination or roughness of the polish surface 91 of the substrate 90,the posture of the polishing member changes pliably, and the polishsurface 91 is uniformly polished with good accuracy.

However, because the drive plate 33 transmits the rotation of thespindle 29 from the head housing 10 to the polishing tool 50, it servesto cause the rotation of the polishing tool integrally with the spindle29. Therefore, the drive plate is required to have a sufficient strengthto transmit the drive torque necessary for such a rotation. For thisreason, the following measures were taken to provide the drive plate 33with sufficient strength.

First, polishing agents comprise polishing liquids such as strong acidsand strong alkalis, and the drive plate 33 can be exposed to suchpolishing liquids. In particular, when the drive plate 33 is detachedfor maintenance, there is a risk of splashed polishing liquid adheringto the drive plate and causing rust or corrosion. Such rust andcorrosion decrease the endurance of the drive plate 33. Another problemis that the rust that appeared on the drive plate contaminates thesubstrate (wafer) 90 or the parts of the polishing apparatus. For thisreason, the drive plate 33 has been produced from a stainless steel(SUS) material, and among stainless steel materials, austeniticstainless steel that has corrosion resistance superior to that ofmartensitic steels was used. From the standpoint of yield strength andelasticity, there are materials superior to stainless steels (forexample, beryllium copper), but such materials require plating forcorrosion protection, and if plating is conducted with the aim ofprotecting the metal against corrosion, the yield strength and elasticproperties thereof are typically degraded due to hydrogen embitterment.Because of this problem and the problem of possible peeling of theplated layer and also because of cost and reliability considerations,stainless steel becomes the most suitable material.

The drive plate 33, as shown in FIG. 5 is produced by forming multipleopenings 33 b, c. The formation of those openings 33 b, c hasconventionally been conducted by laser processing and pressing.Stainless steel materials have a high cold rolling ratio, but thematerial strength typically cannot be expected to increase in quenching.Therefore, hardness and tensile strength have been increased bycompression processing during cold rolling. In other words, the materialstrength was increased by introducing strains and stresses into thecrystal structure by compressive forces. When the drive plate 33 isfabricated by forming the openings 33 b, c by laser processing of suchstainless steel materials, the problem is that the cut surface whichreceived the laser processing heat assumes an annealed state, strainsand stresses contained therein are relieved, and the strength of the cutsurface is decreased. Another problem is that the cut surface which wassubjected to laser processing is a rough processed surface with a largenumber of small peaks and valleys, stress concentration easily occurstherein, and the fatigue strength decreases. On the other hand, when theopenings 33 b, c are formed by pressing, stress relieving by heat as inthe laser processing is avoided, but burrs and shear drops appear on thecut surface and a large number of small peaks and valleys are presenttherein. As a result, stress concentration occurs and strength (inparticular, fatigue strength) decreases.

With the foregoing in view, in accordance with the present invention,the drive plate 33 is produced by processing a sheet of a stainlesssteel material by a chemical removal process (for example, by etching)conducted so as to obtain a disk-like shape shown in FIG. 5 which has around hole 33 a in the center and multiple openings 33 b, c. Whenchemical removal processing such as etching is thus conducted, thedecrease in fatigue strength is small. Therefore, the service life ofthe drive plate obtained by such processing can be longer than that ofthe drive plates produced by the conventional laser processing orpressing, provided that the drive plates have the same shape.

To confirm the above-described assumptions, the inventors have producesa rectangular test piece 110 having a notched portion 111 shown in FIG.6 from a stainless steel material SUS304-CSP-H and tested the fatiguelife of the test piece by applying a tensile cyclic load F to both endsthereof. In the test, fatigue fracture originated in the plane 112passing through the notched portion 111. Accordingly, FIG. 7 shows a S-Ncurve based on the test results, this curve representing therelationship between the equivalent stress amplitude σeq acting upon theplane 112 and the number of cycles N (fatigue life). Line A in thefigure represents test results obtained when the test piece 110 wasproduced by etching, and line B represents test results obtained when itwas produced by laser processing. Those results clearly demonstrate thatthough the materials and shapes were the same, longer fatigue life wasobtained with the test piece produced by etching. Further, theequivalent stress amplitude σeq means a stress amplitude σeq at whichthe equivalent life is obtained when a mean stress σm becomes zero,where the stress with an amplitude σa acts, as shown in FIG. 8, with amean stress σm. The equivalent stress amplitude can be found from thefollowing equation:σeq=σa/{1−(σm/σB)}  (1)where σB is tensile strength.

The inventors have also conducted a comparative fatigue life test inwhich a test piece with the shape shown in FIG. 6 was produced by laserprocessing from different materials. The S-N curves based on the resultsobtained are shown in FIG. 9. In this figure, line C represents testresults for a test piece produced by laser processing from stainlesssteel SUS304-CSP-H in the same manner as described above, and line Drepresents test results for a test piece produced by laser processingfrom stainless steel SUS301-CSP-EH. Those results demonstrated thatSUS301 test piece had longer life than that from SUS304.

As explained hereinabove, in case of etching processing, because strainsare not relieved by processing heat, the problem of strength decrease atthe processed surface is avoided and the processed surface is smooth andhave small peaks and valleys. Therefore, stress concentration hardlyoccurs and the above-described long service life can be obtained.However, when etching is conducted, a rectangular shape with sharpcorners (ridge portions) of the openings and pointed cross section isobtained. Therefore, any impact can damage the corners, thereby formingpeaks and valleys. For this reason, after the openings 33 b, c have beenformed by etching in the drive plate 33, the corners were rounded byconducting after-etching in which the entire mask was stripped and theentire surface was again exposed to the liquid etchant. Barrel polishingmay be employed instead of after-etching.

Further, from the standpoint of fatigue life of the drive plate 33, itis preferred that the surface of the drive plate 33 be smoothed out andthe peaks and valleys causing stress concentration be removed asthoroughly as possible. For this purpose, in the drive plate 33 of thepresent embodiment, the fatigue strength was further increased by mirrorfinishing the surface of the drive plate 33 to obtain a surfaceroughness Ra<0.2 a.

In carbon steels and structural alloys, the correlation between tensilestrength and tension-compression fatigue limit of the material is knownto be within a hatched region sandwiched between lines E and F, as shownin FIG. 10. This relation demonstrates that a strong positivecorrelation can be observed between tensile strength andtension-compression fatigue limit in the vicinity of a tensile strengthof 100 kg/mm² (about 1000 N/mm²), but at a higher tensile strength, thecorrelation decreases. In other words, if a material with a tensilestrength of 100 kg/mm² (about 1000 N/mm²) or less is used, the fatiguelimit changes according to the tensile strength, but a maximum fatiguelife is normally obtained if a material with a tensile strength of 100kg/mm² (about 1000 N/mm²) or higher is used. For this reason, in thepresent embodiment, the drive plate 33 was produced from a stainlesssteel material with a tensile strength of 100 kg/mm² (about 1000 N/mm²)or higher. The two stainless steels SUS301 and SUS304 used for the testillustrated by FIG. 9 had a tensile strength of 100 kg/mm² (about 1000N/mm²) or higher.

With the aforesaid in view, it is preferred that the drive plate 33 beproduced by forming stainless steel SUS301-CSP-EH by etching to obtainthe shape shown in FIG. 5, 10 followed by after-etching and mirrorfinishing to a surface roughness of 0.2 a or less. However, the driveplate in accordance with the present invention is not limited to theabove-described process and a variety of other modes, such as etching ofstainless steel SUS304, can be considered. Specific is shapes aredescribed below on specific examples.

Stacking of drive plates 33 will be explained below.

The effect obtained with the above-described drive plate 33 is that theoccurrence of stress concentration around the openings can besuppressed, strength and endurance with respect to a drive torque orresistance torque during processing conducted after the number or sizeof the openings has been increased can be improved, flexibility of thesupport plate in the up-down direction (direction perpendicular to theplate surface) is increased (rigidity is decreased), and strength andendurance can be ensured. However, when only one drive plate 33 wasused, simply increasing the number or size of the openings or decreasingthe plate thickness was insufficient for reducing the rigidity in theup-down direction (plate thickness direction) and the decrease inrigidity of the drive plate 33 in the up-down direction was at the sametime also connected to the decrease in rigidity of the plate 33 in theinclined direction. More specifically, in the case of the drive plate 33provided with flexibility by openings such as slits, in a linear regionof the microdeformation range, the rigidity in both the up-downdirection (plate thickness direction) and the inclined direction of thedrive plate 33 was found to change almost with the third power of platethickness. This is apparently because both the deformation in theup-down direction and the deformation in the inclined direction proceedas bending of the bridge portions between the openings (slits) and thedeformation components are identical, as shown in FIGS. 11(a), (b).Therefore, if the drive plate 33 is composed of one plate, the rigidityin the inclined direction is difficult to maintain within the prescribedrange at the same time, while reducing the rigidity in the up-downdirection (plate thickness direction) at the same time, and once thepolishing tool 60 (in particular, the polishing pad 65) which is held bythe polishing head 30 via the drive plate 33, as described hereinabove,protrudes beyond the wafer surface 91 and overhangs during swinging, theinclination of the polishing tool 60 cannot be restored and stressesconcentrate at the edge circumference of the wafer.

In accordance with the present invention, the drive plate 33 is composedof at least two stacked plates in order to resolve this problem. If twodrive plates are stacked, not only the rigidity in the up-down directionand tilting direction are simply doubled, but also +αrigidity isprovided in the tilting direction by a parallel elastic effect(described hereinbelow). As a result, the rigidity in the up-downdirection (plate thickness direction (pressurizing direction)) and therigidity in the tilting direction of the stacked drive plates 33 can becontrolled independently and set to attain the desired balance.Furthermore, for example, when the rigidity in the up-down direction isincreased by employing two drive plates and the allowed range ofpressure change accompanying the wear of the polishing pad 65 isexceeded, using a stack of two plates with a thickness 1/³{squareroot}{square root over ( )}2 that of one drive plate 33 which is withinthe allowed range makes it possible to increase the rigidity in theinclined direction, while maintaining the rigidity in the up-downdirection, and the polishing tool 60 can be effectively prevented fromtilting.

Furthermore, stacking two drive plates 33 is also effective forsuppressing the below-described chatter vibrations occurring duringpolishing. The two drive plates 33 are stacked upon turning one withrespect to another through a prescribed angle in the XY plane shown inFIG. 1. The prescribed angle as referred to herein is set according tothe number of slits disposed on concentric circles in thecircumferential direction of the drive plates. More specifically, in thedrive plate 33 shown in FIG. 5, three slits 33 d are provided onconcentric circles. Therefore, vibrations with three wavelengths per onecycle are produced, one wavelength is 360°:3 wavelengths=120°, and iftwo drive plates 33 are arranged with a 120°:2=60° shift (halfwavelength), then the peaks and valleys of the vibrations will overlap,interference will occur between the two plates, and an attenuationeffect will be produced. FIGS. 12, 13 illustrate a case in which twodrive plates 33′ similar to that shown in FIG. 5, but having five slitsin one circle are shifted with respect to each other and deformed in theinclined direction. In this case, the drive plates 33′ are shiftedthrough the prescribed angle of 36° calculated by the above-describedcomputational method (360°:5 wavelengths:2), and the vibrations of thedrive plate 33′ shown in FIG. 12 and the drive plate 33′ shown in FIG.13 which are shifted by 36° mutually interfere and attenuate each other.In other words, if the two drive plates 33 are so arranged that thevibrations in the opposing positions of the plates are in almostopposite phases, then the chatter vibrations can be suppressed.

In the explanation hereinabove, drive plates 33, 33′ shown in FIG. 3 orFIGS. 12, 13 similar thereto were considered, but drive plates of othershapes can be also employed. In particular, those drive plates thatcould not be employed in the conventional systems composed of one driveplate can be used in stacks of a plurality thereof. Further, the methodsfor processing and materials of the two drive plates 333, 433 that willbe discussed as examples can be understood by referring to theexplanation of the drive plate 33 shown in FIG. 5 that was discussedhereinabove.

The drive plate 333 provided with multiple spiral grooves 333 a will beexplained with reference to FIG. 14. The advantage of this plate 333 isthat the rigidity in the up-down direction (direction of paper sheetsurface) can be greatly reduced because one groove 333 a can have a verylarge length. On the other hand, when a rotary force acted in the Wdirection shown in FIG. 14, the bridge portions were easily buckled. Asa result, the conventional system composed of one drive plate could notbe used. On the other hand, the drive plate 333 shown in FIG. 14features a high strength against the rotary force in the directionopposite to the W direction. Therefore, if a stacking method inaccordance with the present invention is used, then stacking with thedrive plate 333 having spiral grooves 333 b (see FIG. 15) with a windingdirection opposite to that of the spiral grooves 333 a shown in FIG. 14will make it possible to obtain a high rigidity of one of the two platesand to avoid buckling, regardless of the direction of rotary forceaction.

Furthermore, drive plates 433 shown in FIGS. 16, 17 can be also employedas modification examples of the drive plates 333 equipped with thespiral grooves 333 a shown in FIGS. 14, 15. The drive plates 433 shownin FIGS. 16, 17 correspond to drive plates 333 shown in FIGS. 14, 15,respectively.

An embodiment of the method for the fabrication of a semiconductordevice in accordance with the present invention will be described below.FIG. 18 is a flow chart illustrating the semiconductor devicefabrication process. When the semiconductor fabrication process isstarted, first, in step S200, an adequate treatment process is selectedfrom those of the below-described steps S201 to S204 and the processingflow advances to that step.

Here, step S201 is an oxidation process for oxidizing the substratesurface. Step S202 is a CVD process for forming an insulating film ordielectric film on the substrate surface by CVD or the like. Step S203is an electrode formation process for forming electrodes on the wafer bydeposition or the like. Step S204 is an ion implantation process forimplanting ions into the wafer.

After the CVD process (S202) or electrode formation process (S203), theprocessing flow advances to step S205. Step S205 is a CMP process. TheCMP process comprising a step of flattening the interlayer insulatingfilm, polishing the metal film present on the semiconductor devicesurface, or polishing the dielectric film with the polishing apparatusin accordance with the present invention. A damascene process can bealso employed.

Upon completion of the CMP process (S205) or oxidation process (S201),the processing flow advances to step S206. Step S206 is aphotolithography process. In this process, a resist is coated on thewafer, the circuit pattern is baked onto the wafer by exposure using anexposure device, and the exposed wafer is developed. Further, the nextstep S207 is an etching process in which portions other than thedeveloped resist image are removed by etching, then resist peeling isconducted, and the resist that became unnecessary after etching wascompleted is removed.

Then, in step S208, a decision is made as to whether the entirenecessary process was completed, and if it were not completed, theprocessing flow returns to step S200, subsequent steps are repeated, anda circuit pattern is formed on the wafer. If a decision were made instep S208 that the entire process has been completed, the processingends.

With the method for the fabrication of semiconductor devices inaccordance with the present invention, processing accuracy and yield ofwafers are increased because the polishing apparatus in accordance withthe present invention is used in the CMP process. As a result,semiconductor devices can be fabricated at a lower cost than with theconventional method for the fabrication of semiconductor devices.Furthermore, the polishing apparatus in accordance with the presentinvention may be also used in CMP of semiconductor device fabricationprocesses other than the above-described semiconductor devicefabrication process. The semiconductor devices fabricated by thesemiconductor device fabrication method in accordance with the presentinvention are high-yield and low-cost semiconductor devices.

In the above-described embodiment of the processing apparatus inaccordance with the present invention, the explanation was conductedwith respect to a CMP apparatus using a plurality of drive plates andhaving a slit pattern formed by a chemical removal process. However, thepresent invention is not limited to such an apparatus, and it is obviousto a person skilled in the art that the technological concept of thepresent invention can be easily diverted to other processing apparatuseswhich require that the relative positions of the tool and processingobject be traced.

As described hereinabove, arranging a plurality of support plates (driveplates) of a processing apparatus in a row in accordance with thepresent invention makes it possible to attain “the decrease in rigidityin the up-down direction (plate thickness direction)” and at the sametime “to ensure the appropriate rigidity in the inclined direction”,while “ensuring rigidity and endurance against the torque or swingingdirection”. Further, with the processing apparatus in accordance withthe present invention, the so-called chatter vibrations generated in thetool—tool holder configurations can be also suppressed.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

RELATED APPLICATIONS

This application claims the priority of Japanese Patent ApplicationNo.2003-155319 filed on May 30, 2003 which is incorporated herein byreference.

1. A processing apparatus comprising an object holding unit for holdinga processing object, a tool holding unit for holding a tool forprocessing said processing object, and a relative movement mechanism forcausing relative movement of the processing object held in said objectholding unit and the tool held in said tool holding unit, whilemaintaining contact therebetween, wherein said object holding unitand/or said tool holding unit are composed of a plurality of supportplates of almost flat shape having elastic property which are arrangedin a row.
 2. The processing apparatus according to claim 1, wherein saidplurality of support plates are disposed by stacking in a row in theplate thickness direction.
 3. The processing apparatus according toclaim 2, wherein said plurality of support plates are disposed by liningup parallel to each other with a prescribed spacing and stacking in theplate thickness direction.
 4. The processing apparatus according toclaim 2, wherein said plurality of support plates have formed therein atleast one opening providing them with said elastic property, and saidplurality of support plates are disposed by stacking in the platethickness direction, so that the openings in said support plates thatadjoin each other in the vertical direction are shifted with respect toeach other.
 5. The processing apparatus according to claim 2, wherein anopening providing with said elastic property is formed in at least twosupport plates of said plurality support plates, and the patterns ofsaid openings in said two support plates differ, if viewed from theplate thickness direction of said support plates.
 6. The processingapparatus according to claim 4 or 5, wherein at least part of saidopenings is formed by a chemical removal process.
 7. The processingapparatus according to claim 6, wherein said chemical removal process isetching.
 8. The processing apparatus according to claim 6, wherein anaverage surface roughness of said support plates subjected to saidchemical removal process is 0.2 a or less.
 9. The processing apparatusaccording to claim 6, wherein said openings formed by said chemicalremoval process are chamfered by barrel polishing or after-etching. 10.The processing apparatus according to claim 4 or 5, wherein saidopenings are composed of curved or linear slits and almost round openportions formed at the ends of said slits and having a diameter largerthan the width of said slits.
 11. The processing apparatus according toclaim 4 or 5, wherein said openings are composed of curved or linearslits and opening portions with a shape reducing shear stresses to whichsaid support portion is subjected when said processing object isprocessed with said tool.
 12. The processing apparatus according to anyof claims 1 to 5, wherein said support plate is produced from a materialwith a tensile strength of 1000 N/mm² or higher.
 13. The processingapparatus according to claim 12, wherein said material is an austeniticstainless steel.
 14. The processing apparatus according to any of claims1 to 5, wherein the fatigue life of said support plate based on themaximum value of the equivalent stress amplitude to which said supportportion is subjected when said processing object is processed with saidtool is no less than the actual use period of said processing apparatus.15. The processing apparatus according to any of claims 1 to 5, whereinat least said support plate is placed in vacuum environment orenvironment of a substance with low chemical reactivity with respect tothe constituent materials thereof during processing of said processingobject with said tool.
 16. A method for the fabrication of asemiconductor device, wherein said processing object is a semiconductorwafer, and the surface of said semiconductor wafer is planarized byusing the processing apparatus described in any of claims 1 to
 5. 17. Asemiconductor device fabricated by the method for the fabrication of asemiconductor device described in claim 16.